Die for extrusion presses



Sept. 8, 1953 l. T. BENNETT 2,651,411

DIE FOR EXTRUSION PRESSES Filed Oc. 16, 1948 3 Sheets-Sheet 2 Sept- 8, 1953 1; T. BENNETT 2,651,411

DIE FOR EXTRUSION PRESSES Filed Oct.' 16, 1948 3 Sheets-Sheet 5 I :7i/vena z.- Irv ng 175621716513, @ivm 7M 71M2ML/@Uhligg Patented Sept. 8, `1953 DIE FOR EXTRUSION PRESSES Irving T. Bennett, Baltimore, Md., assignor to Revere Copper and Bra N. Y., a corporation of ss Incorporated, Rome, Maryland AApplication October 16, 1948, Serial No. 54,846

K 1 Claim.

My invention relates to extrusion presses.

The present invention has among its objects the provision of a die of improved construction for simultaneously extruding a plurality of hollow shapes from a single billet of metal, such as aluminum, separate streams of which are capable of being mixed under high pressure to form a, homogeneous mass.

The invention will be best understood from the following description when read in the light of the accompanying drawings, the scope of the invention being more particularly pointed out in the appended claim.

In the drawings:

Fig. l is a longitudinal vertical section more or less diagrammatically showing a fragment of an extrusion press having an improved die according to the invention, this figure also illustrating a step in the extrusion process;

Fig. 2 is an elevation of the improved die as viewed from the left of said die in its position occupied in Fig. 1;

Fig. 3 is a section on the line 3-3 of Fig. 2, with parts omitted;

Fig. 4 is a bottom view of one of the mandrel carrying parts of the improved die as viewed in the position which said part occupies in Fig. 3;

Fig. 5 is a, plan of one of the die parts having the die orifice according to Figs. 1, 2 and 3 as viewed in the position which said part occupies in Fig. 3;

Fig. 6 is a bottom view of the die part according to Fig. 5;

Fig. 7 is a transverse section of a tube representing an example of the shape to be extruded by the improved die;

Fig. 8 is a transverse section of a modied form of the tube according to Fig. 7;

Fig. 9 is a view corresponding to Fig. 2 of a prior art die;

Fig. 10 is a. section on the line III-I0 of Fig. 9; and

Fig. l1 is a section on the line I I I I of Fig. 10.

As will be understood by those skilled in the art, when extruding solid` bars and like shapes the die of the extrusion press need have but a die oriiice of cross-section corresponding to the exterior cross-sectional form of the shape. However, when the shape extruded by the press is hollow, the die must have a die -orice of cross-section corresponding to the cross-sectional form of the exterior surface of the shape, and, received by such die orifice, must have a mandrel of cross-section corresponding to the cross-sectional form of the interior surface of the shape. For example, in extruding the hollow shape exemplified by the tube I ,(Fig. '7) the die must have a die orice dening the exterior surface 3 of .the tube, and must have a mandrel defining the interior surface 5 of the tube. Shapes of other cross-section as, for example, the tube I (Fig. 8) having the longitudinally extending opening 9, also require use of a mandrel, which latter, or the die orice, in the case of such a tube must be formed with a rib or the like for dening the form of such longitudinally extending opening. The use of a mandrel is imposed in this latter case because, were it attempted to form the die with a die orifice of cross-section defining the entire cross-sectional form of both the interior and exterior wall surfaces of the tube including those of the longitudinally extending opening 9, the thickness of the metal of the die defining such longitudinally extending opening would be too small under the high extrusion pressure required to afford sufficient strength for supporting the metal dening the rest of the interior form of the tube. Such tubular shapes, and shapes having a longitudinally extending opening requiring the use of a mandrel for extruding them, are in the art termed hollow shapes, which term is employed herein in such sense.

In the embodiment of the invention illustrated there is provided a die body comprising ahousing II carrying a plurality (herein four) of like pairs of cooperating die parts I3 and I5. As shown, the housing is shown with a plurality of openings I'I, one for each pair of die parts I3 and I 5, which openings are of circular cross-section and extend through said housing from its upper face I8 to its lower face I9 as viewed in Fig. 3. The portion 2| of each of these openings adjacent the face I8 is of enlarged diameter so as to form intermediate the length of the opening an annular shoulder 23 opposed to said face.

In the enlarged diameter portion 2| of each of the openings I'I of the housing II is removably received one of the die parts I3 and one of the die parts I5, these parts having exterior surfaces itting the lateral cylindrical walls of that portion of the opening. 'Ihe die part I3 at one end rests adjacent its periphery upon the annular shoulder 23 presented by the housing. This die part is formed with an axial opening 25 which adjacent the face of said part opposite the shoulder 23 is formed with an annular rib 21 provided with an oriiice 29. This orice V29 defines the exterior form of the shape to be extruded, said shape for convenience of illustration being shown as a square tube I according to Fig. 7.

Each die part I5 at one end rests against the adjacent face of the associatedpdie part I3, the contacting faces of the two parts preferably being formed with the cooperating interfitting longitudinally projecting anges 3| and v33 for facilitating holding them in axial alignment,Y VThe face of the die part I5 adjacent the die part VI3 3 is formed with what from one aspect may be considered an annular recess (Fig. 3) the inner walls of which are constituted by the outer longitudinally extending surfaces of a mandrel 3l. The forward end of this mandrel is received within the die orifice 2S in spaced relation to the walls of that orifice, the mandrel being of such cross-sectional shape as to denne the interiorV form of the tube or other'shape to ber-extruded. Exteriorly the mandrel carrying' die part l5 is formed with a plurality, herein four, of longitudinally extending grooves 39 which at their inner ends communicate with the recess 35. From another aspect the die part l5 may be said toconsist of the mandrel 31 carrying a plurality of radially projecting longitudinally extending ribs 4l. (Fig-s. 2 and 4) in quartering relation of each other, which ribs at their outer extremities fit the lateral walls of the enlarged diameter portion 2l of the opening in the housing H, the lower ends of which ribs are provided with grooves collec tively forming with the adjacent portions of the spaces between the ribs the recess 35.

As illustrated, for preventing relative rotation between the die parts I3 and l5 they are shown as keyed together by a pin43 which may be iixed to the part i3 and Ybe removably received in an opening 44 in the part I5, the die part I5 being preferably keyed by a pin 45 to the housing Il for preventing it, and the die part I3 keyed to it, from rotation relative to the housing, the pin i5 being preferably fixed to the part l5 and removable with the latter from the housing.

As shown in Fig. l, in accordance with common practice the die is removably mounted in the bore 41 of a die holder 49, which holder is removably mounted in a ring 5G removably carried by a support 5I movably mounted on the frame of the extrusion press, the support having an upwardly projecting portion 53 between which and the die and die holder are placed, removable blocks 55 and 5l for holding the face of the die opposite the blocks against the end of the extrusion press cylinder 59. This cylinder in the usual manner is provided with a bore 6l for the extrusion press ram S3 and dummy block 65, the latter during the extrusion operation bearing against a billet 57 such as aluminum. In operation pressure of the ram G3 on the billet 51 forces the metal of the billet through the grooves 39 of the die part l5 into the mixing chamber presented by the recess 35 of that part. In this chamber the streams of metal passing through the grooves are mixed, or, as it is sometimes termed welded under the high pressure existing to form a homogeneous mass of metal, which metal is forced through the space between the mandrel 3'! and the Walls of the die orice 29 of the die part i3 to form the tubes l, these tubes passing through the openings l'i of the housing H and through aligned openings 69, 'll and 'I3 in the blocks 55 and 51 and projection 53, respectively, until the metal of the billet is substantially exhausted. The support 5l, with the blocks 55 and 51, ring 55, die holder 49 and the die, is then moved forward relative to the ram cylinder 59, carrying with them the unextruded butt end of the billet, which latter is then sheared off close to the adjacent face of the die. Then, after retraction of the ram, a fresh billet may be entered into the ram cylinder and the support 5l retracted to place the parts again in their positions shown by Fig. l. Extruding this fresh billet forms continued lengths of the tubes or other shapes l welded at their ends to the ends of those formed by the preceding extrusion operation. If desired, as is usually the case, the weld between the ends of the tubes may be eut out as the extrusion operation is perf ormed so as to separate the lengths formed by successive extrusion operations. These operations; of extruding the tubes from successive billets may be continued indelinitely without its being necessary to clear the die.

It will be observed that in the construction above described a die is provided for simultanem ously extruding a plurality of like hollow shapes from a single billet, which die comprises a die body formed to present a plurality of separate non-communicating internal chambers in which the streams of metal entering said chambers from the billet are mixed to form separate hemogeneous masses of metal, which masses are separately forced through the spaces between cooperating mandrels and die orifices defining the cross-sectional forms of the shapes.

Heretofore it has been proposed to extrude a plurality of shapes from a single billet by use o1' the die illustrated by Figs. 9, li) and il. This prior art die comprises the separable parts 'i5 and l?, the parts 'i5 being formed with a plurality or portholes T9 through which metal of the billet, is forced by the ram into the annular chamber Si formed in the part 1l' and closed by the part From this chamber lead all the` die orifices 3S cor responding to the exterior form of the shape 'seing extruded as, for example, square tubes i according to Fig. '1. The housing part "iii in 's prior art die integrally carries the mandrel 'f which projectV forward into the openings so as to denne the interior form of the shape extruded.

t will be observed that the prior art die above described distinguishes from the die according to the present invention in that, among other things, in the prior art die a single mi f' chamber for the metal is provided for plof die openings foreXtr-uding hollow shap stead of a separate mixing chamber for each plurality of die openings for extruding s shapes.

It has been found that by employing the separate mixing chambers in accordance with cants invention many unexpected and unc'rvi. valuable results are secured. In the first it has been found that with the separate in chambers lower extrusion pressures are for extrudinga plurality of hollow alurnruini shapes of given cross-section than when emplcying a die having a single mixing chamber for estruding the same number of the saine shapes, this despite the transverse cross-sectional area of the single mixing chamber of the prior art die being greater than the aggregate transverse cross-sectional area of the total number of mixing chainbers of the die according to the present invention and even Where at the same time the aggre gate area of the total number of portholes 'i9 ci the prior art die is greater than the aggregate cross-sectional area afforded by the total number of grooves 33 of the die according to the present invention. This lower extrusion pressure increases the life of. the die, permits the use of expensive die back-.up blocks, and most'impcrtantly avoids distortion and deflection of the mandrels so that a more accurate and uniform product in respect to dimensions will be secured. It has also been found that a lower temperature of the aluminum billet'is permissible with the improved die aS cQmPFrl-i @0 the prior art die, it

less

not being necessary to render the metal as plastic with the improved die as with the prior art die, which results when the improved die is employed in savings in heating costs and, as in the case of the reduced pressure necessary, also acts to secure a longer life of the die. Furthermore, the lower pressures and temperatures necessary when using the improved die for extruding aluminum permit the physical properties of the product to be more easily controlled during the extrusion operation, with the overall result of insuring a better product in respect to such properties. Still further, not only are lower temperatures and pressures required with the improved die, as compared to the prior art die, but a greater speed of extrusion of the aluminum can be secured despite such lower pressures and temperatures. In practice, when employing the prior art die, if the extrusion pressure required is near the maximum capable of being exerted by the press the latter will cease to operate if one die opening clogs, but when employing the die having separate mixing chambers for extruding the same number of the same shapes the press because of the lower pressures then required will not cease to operate if one die opening should clog for it can then take care of the increase in pressure necessary to extrude with the remaining unclogged die openings, Also extreme difficulty has been experienced in designing the prior art die with a single mixing chamber in respect to securing the necessary condition of causing the metal to extrude from all the die openings at substantially the same rate, the securing of such condition with the prior art die requiring the exercise of great skill and nicety of design on the part of the die maker. Such tendency of the metal to extrude from the die openings at different rates, it has been found, is substantially absent with a die according to the present invention employing a separate mixing chamber for each die opening, with the result that the improved die can be produced with greater facility and at lower cost. Still further, the cost of producing the improved die is reduced as compared to the prior die, and greater accuracy of manufacture is assured, because the improved die for the most part is formed of much smaller pieces of steel than the prior die. The making of the die in the way described gives it great versatility in respect to adapting it for extruding selected shapes, because the same may be secured by merely substituting small parts for each other, rather than substituting a complete die as would be the case with the prior die.

As an example of the above advantages secured by the improved die, it has been found, that where the available fluid pressure to be applied to the ram of the press limits the maximum size of the aluminum billet to one of i1/2 inches diameter when employing a multiple die having four openings and a single mixing chamber according to the prior art, an 8 inch diameter billet, in other Words, one having about 31A, times as much metal for a given length of rain cylinder bore, may be employed for the same number of die openings of the same shape and size when the improved die having separate mixing chambers is employed. This increase in the size of the billet according to this example will secure about 31A, times the amount of hollow shapes produced during a single extrusion operation, and for a given amount of extruded shapes produced reduces to about one-third the overall loss in time required for shearing off the billet butts and inserting fresh billets between extruding operations. As a further example of the advantages secured in practice by use of the improved die it has been found, that where a hot aluminum billet 6 inches in diameter and 21 inches long required from 3300 to 3600 pounds per square inch extrusion pressure for a die having four openings and a single mixing chamber according to the prior art die, the improved die according to the present invention having the same number of die openings for extruding exactly the same shapes required an extrusion pressure of but 2500 to 2700 pounds per square inch with a decrease in the necessary temperature of the billet from 925 to 850 F. and secured an increase in the linear speed of extrusion of the shapes from 40 to 90 feet per minute.

It will be understood that although the die illustrated is designed for simultaneously extruding four hollow shapes it may be designed for extruding a greater 0r lesser number. It will also be understood that, although as illustrated the die is designed for extrudmg square tubes, other forms of hollow shapes may be extruded with equal facility. Further, it will be understood that within the scope of the appended claim wide deviations may be made from the form of the invention illustrated and described without departing from the spirit of the invention.

I claim:

A die ror simultaneously extruding a plurality of like hollow aluminum shapes from a single billet comprising a housing iormed with a plurality of like openings, each of which openings extends from one face of said housing to tne other and is formed to present an annular siioulder intermediate its length, separate like nrst die parts each removably received by and iittlng one of said openings, respectively, and resting at one end portion adiacent its periphery against said annular shoulder, each of which die parts is formed with a die orifice delining the external form of one of said like shapes, separate like second die parts each removably received by and Vritting one of said openings, respectively, and resting at one end portion adjacent its periphery against said first die part in that opening, each of said second die parts being formed with a inandrel cooperating with the die orifice oi' the adjacent first die part, which mandrel derines the internal form of one of said like shapes, that face of each of said second die parts which is adjacent the associated first die part being formed to present a recess continuously and symmetrically surrounding said mandrel throughout the entire peripheral extent of said mandrel and communicating with the die orifice of said rirst die part throughout the entire peripheral extent of such orice, the mandrel defining the inner lateral side of said recess throughout the full circumferential extent of such side, each of said second die parts being formed with a plurality of uniformly distributed exterior longitudinally extending like grooves communicating with the adjacent recess for the full radial width of the latter and opening on the end face of said part opposite said recess.

IRVING T. BENNETT.

References Cited in the file of this patent UNITED STATES PATENTS Couchman Mar. 17, 1942 

